Re: [PATCH] block: zoned: fix harmless maybe-uninitialized warning

From: Damien Le Moal
Date: Sun Oct 23 2016 - 19:38:58 EST



On 10/22/16 00:42, Arnd Bergmann wrote:
> The blkdev_report_zones produces a harmless warning when
> -Wmaybe-uninitialized is set, after gcc gets a little confused
> about the multiple 'goto' here:
>
> block/blk-zoned.c: In function 'blkdev_report_zones':
> block/blk-zoned.c:188:13: error: 'nz' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> Moving the assignment to nr_zones makes this a little simpler
> while also avoiding the warning reliably. I'm removing the
> extraneous initialization of 'int ret' in the same patch, as
> that is semi-related and could cause an uninitialized use of
> that variable to not produce a warning.
>
> Fixes: 6a0cb1bc106f ("block: Implement support for zoned block devices")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> block/blk-zoned.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 667f95d86695..472211fa183a 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -80,7 +80,7 @@ int blkdev_report_zones(struct block_device *bdev,
> unsigned int i, n, nz;
> unsigned int ofst;
> void *addr;
> - int ret = 0;
> + int ret;
>
> if (!q)
> return -ENXIO;
> @@ -179,14 +179,12 @@ int blkdev_report_zones(struct block_device *bdev,
>
> }
>
> + *nr_zones = nz;
> out:
> bio_for_each_segment_all(bv, bio, i)
> __free_page(bv->bv_page);
> bio_put(bio);
>
> - if (ret == 0)
> - *nr_zones = nz;
> -
> return ret;
> }
> EXPORT_SYMBOL_GPL(blkdev_report_zones);

Reviewed-by: Damien Le Moal <damien.lemoal@xxxxxxx>

--
Damien Le Moal, Ph.D.
Sr. Manager, System Software Research Group,
Western Digital Corporation
Damien.LeMoal@xxxxxxx
(+81) 0466-98-3593 (ext. 513593)
1 kirihara-cho, Fujisawa,
Kanagawa, 252-0888 Japan
www.wdc.com, www.hgst.com